I used to teach at a college where it was expected the instructors 'friend' their students on Facebook, give their personal email addresses (not just their college emails), add them to their tweet list (and it was encouraged to be on Twitter), etc. Some instructors even went to student's parties. A recent video has a student stating his instructor is his best friend. I never did any of that. To me, this is fraught with peril. One instructor literally tweeted how proud he was that he could take a photo and tweet while driving. This sends the wrong message to the students. They look up to us (most of the time) and some want to emulate us. I could see potential lawsuits coming from that if a student got into a wreck, hurt herself or someone else, and said "But my instructor does it". Students will ask me to friend them, but I politely refuse.